Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 63: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles IV (jointly with TT)
O 63.9: Vortrag
Donnerstag, 29. März 2012, 12:45–13:00, HE 101
Accurate electronic structure calculation on transition metal defects in SiC by HSE06+U functional — •Viktor Ivády1 and Ádám Gali1,2 — 1Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest, Hungary — 2Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
Relatively little is known about transition metal impurities in semiconductors. The accurate treatment of these systems require the exact description of strongly correlated partially occupied d and f shells of the impurities in host materials of sp3 bonds. In our study we investigate the electronic structure of transitional metals (Ti, V and Cr) in 4H-SiC by means of PBE (semi)local functional and HSE06 range separated hybrid functional calculations in 576-atom supercell where experimental data are available for these impurities. While HSE06 functional yielded superior results over (semi)local functionals regarding the Mott-insulators with correlated states our results show that HSE06 are not sufficiently accurate for the chosen isolated transition metal defects. The application of HSE06+U functional allow us to apply orbital dependent corrections on the correlated orbitals in the experimental band gap of SiC. We chose the U to fulfill the generalized Koopmann’s and Janak’s theorems that is presumably an "exact" functional of the system. Our investigations show that U should be energy dependent and its acutal value depends also on the given defect configuration even for the same type of the impurity. We compare the experimental and calculated transition levels obtained by the "exact" functional.